title: Antitumor effects of OSU-2S, a nonimmunosuppressive analogue of FTY720, in hepatocellular carcinoma.
abstract: Accumulating evidence suggests the therapeutic potential of the immunosuppressive agent FTY720 (fingolimod) in hepatocellular carcinoma (HCC). Based on our previous finding that FTY720 mediates apoptosis in HCC cells by activating reactive oxygen species (ROS)-protein kinase Cδ (PKCδ) signaling independent of effects on sphingosine-1-phosphate (S1P) receptors, we embarked on the pharmacological exploitation of FTY720 to develop a nonimmunosuppressive analogue with antitumor activity. This effort led to the development of OSU-2S, which exhibits higher potency than FTY720 in suppressing HCC cell growth through PKCδ activation. In contrast to FTY720, OSU-2S was not phosphorylated by sphingosine kinase 2 (SphK2) in vitro, and did not cause S1P1 receptor internalization in HCC cells or T lymphocyte homing in immunocompetent mice. Although devoid of S1P1 receptor activity, OSU-2S exhibited higher in vitro antiproliferative efficacy relative to FTY720 against HCC cells without cytotoxicity in normal hepatocytes. Several lines of pharmacological and molecular genetic evidence indicate that ROS-PKCδ-caspase-3 signaling underlies OSU-2S-mediated antitumor effects, and that differences in the antitumor activity between FTY720 and OSU-2S were attributable to SphK2-mediated phosphorylation of FTY720, which represents a metabolic inactivation of its antitumor activity. Finally, OSU-2S exhibited high in vivo potency in suppressing xenograft tumor growth in both ectopic and orthotopic models without overt toxicity.
  
  
  CONCLUSIONS
  Using the molecular platform of FTY720, we developed OSU-2S, a novel PKCδ-targeted antitumor agent, which is devoid of S1P1 receptor activity and is highly effective in suppressing HCC tumor growth in vivo. These findings suggest that OSU-2S has clinical value in therapeutic strategies for HCC and warrants continued investigation in this regard.
authors.affiliation: Division of Medicinal Chemistry, College of Pharmacy, Ohio State University, Columbus, OH 43210, USA. chen.844@osu.edu
authors.forename: Hany A
authors.initials: HA
authors.lastname: Omar
authors.forename: Chih-Chien
authors.initials: CC
authors.lastname: Chou
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Berman-Booty
authors.forename: Yihui
authors.initials: Y
authors.lastname: Ma
authors.forename: Jui-Hsiang
authors.initials: JH
authors.lastname: Hung
authors.forename: Dasheng
authors.initials: D
authors.lastname: Wang
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kogure
authors.forename: Tushar
authors.initials: T
authors.lastname: Patel
authors.forename: Luigi
authors.initials: L
authors.lastname: Terracciano
authors.forename: Natarajan
authors.initials: N
authors.lastname: Muthusamy
authors.forename: John C
authors.initials: JC
authors.lastname: Byrd
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Kulp
authors.forename: Ching-Shih
authors.initials: CS
authors.lastname: Chen
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D000068876:Fingolimod Hydrochloride; D022781:Hepatocytes / Q000187:drug effects / Q000473:pathology; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D051379:Mice; D008819:Mice, Nude; D011409:Propylene Glycols / Q000494:pharmacology*; D051745:Protein Kinase C-delta / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; C560545:OSU-2S; D011409:Propylene Glycols; D017382:Reactive Oxygen Species; D051745:Protein Kinase C-delta; D053148:Caspase 3; D000068876:Fingolimod Hydrochloride; D013110:Sphingosine